Screen‐Printed Silver‐Nickel Hybrid Contacts for SiO x /n + ‐Poly‐Si Layers in TOPCon Solar Cells

ABSTRACT Tunneling Oxide Passivated Contact (TOPCon) solar cells have emerged as a dominant technology in the global photovoltaic market due to their superior efficiency and long‐term stability. However, the metallization process continues to rely predominantly on costly silver (Ag) pastes, making cost reduction a prerequisite for their continued large‐scale deployment. In this study, nickel (Ni) particles were strategically incorporated into conventional Ag pastes to reduce noble metal consumption without compromising device performance. To address the inherent challenges of Ni—namely its lower bulk conductivity and work function mismatch with the silicon emitter—the Ni/Ag weight ratio was systematically optimized. SEM and EDS analyses confirmed a highly uniform distribution of Ag and Ni within the printed features. Notably, the Ag‐Ni hybrid paste exhibited enhanced rheological properties, yielding grid lines with a higher aspect ratio compared to benchmark pure‐Ag pastes. High‐resolution TEM images of the contact interface revealed a unique morphology where Ni particles were encapsulated by Ag colloids, preventing direct Ni‐Si contact, whereas interfacial gaps were effectively filled by glass frit. At an optimized Ni content of 10 wt%, the solar cells demonstrated optimal performance, achieving an average contact resistivity of 2.79 mΩ.cm 2 . In a mass‐production environment, the fill factor ( FF ) and efficiency ( E ff ) exhibited only minimal reductions of 0.36% and 0.1%, respectively, compared to the reference cell. The optimized cells maintained a high conversion efficiency of over 26.5%, with an open‐circuit voltage of 0.744 V, a short‐circuit current density of 41.47 mA/cm 2 , and a FF of 87.10%. Furthermore, the robust reliability in internal cell‐level testing exhibited less than 5% performance degradation after a 48‐h damp heat test under the conditions of 45°C/95% RH. These results demonstrate a viable pathway toward cost‐effective metallization for next‐generation TOPCon solar cells.